001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.tftp;
019
020import java.net.DatagramPacket;
021import java.net.InetAddress;
022
023/***
024 * A final class derived from TFTPPacket definiing the TFTP Error
025 * packet type.
026 * <p>
027 * Details regarding the TFTP protocol and the format of TFTP packets can
028 * be found in RFC 783.  But the point of these classes is to keep you
029 * from having to worry about the internals.  Additionally, only very
030 * few people should have to care about any of the TFTPPacket classes
031 * or derived classes.  Almost all users should only be concerned with the
032 * {@link org.apache.commons.net.tftp.TFTPClient} class
033 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
034 * and
035 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
036 * methods.
037 *
038 *
039 * @see TFTPPacket
040 * @see TFTPPacketException
041 * @see TFTP
042 ***/
043
044public final class TFTPErrorPacket extends TFTPPacket
045{
046    /*** The undefined error code according to RFC 783, value 0. ***/
047    public static final int UNDEFINED = 0;
048
049    /*** The file not found error code according to RFC 783, value 1. ***/
050    public static final int FILE_NOT_FOUND = 1;
051
052    /*** The access violation error code according to RFC 783, value 2. ***/
053    public static final int ACCESS_VIOLATION = 2;
054
055    /*** The disk full error code according to RFC 783, value 3. ***/
056    public static final int OUT_OF_SPACE = 3;
057
058    /***
059     * The illegal TFTP operation error code according to RFC 783, value 4.
060     ***/
061    public static final int ILLEGAL_OPERATION = 4;
062
063    /*** The unknown transfer id error code according to RFC 783, value 5. ***/
064    public static final int UNKNOWN_TID = 5;
065
066    /*** The file already exists error code according to RFC 783, value 6. ***/
067    public static final int FILE_EXISTS = 6;
068
069    /*** The no such user error code according to RFC 783, value 7. ***/
070    public static final int NO_SUCH_USER = 7;
071
072    /*** The error code of this packet. ***/
073    int _error;
074
075    /*** The error message of this packet. ***/
076    String _message;
077
078    /***
079     * Creates an error packet to be sent to a host at a given port
080     * with an error code and error message.
081     *
082     * @param destination  The host to which the packet is going to be sent.
083     * @param port  The port to which the packet is going to be sent.
084     * @param error The error code of the packet.
085     * @param message The error message of the packet.
086     ***/
087    public TFTPErrorPacket(InetAddress destination, int port,
088                           int error, String message)
089    {
090        super(TFTPPacket.ERROR, destination, port);
091
092        _error = error;
093        _message = message;
094    }
095
096    /***
097     * Creates an error packet based from a received
098     * datagram.  Assumes the datagram is at least length 4, else an
099     * ArrayIndexOutOfBoundsException may be thrown.
100     *
101     * @param datagram  The datagram containing the received error.
102     * @throws TFTPPacketException  If the datagram isn't a valid TFTP
103     *         error packet.
104     ***/
105    TFTPErrorPacket(DatagramPacket datagram) throws TFTPPacketException
106    {
107        super(TFTPPacket.ERROR, datagram.getAddress(), datagram.getPort());
108        int index, length;
109        byte[] data;
110        StringBuilder buffer;
111
112        data = datagram.getData();
113        length = datagram.getLength();
114
115        if (getType() != data[1]) {
116            throw new TFTPPacketException("TFTP operator code does not match type.");
117        }
118
119        _error = (((data[2] & 0xff) << 8) | (data[3] & 0xff));
120
121        if (length < 5) {
122            throw new TFTPPacketException("Bad error packet. No message.");
123        }
124
125        index = 4;
126        buffer = new StringBuilder();
127
128        while (index < length && data[index] != 0)
129        {
130            buffer.append((char)data[index]);
131            ++index;
132        }
133
134        _message = buffer.toString();
135    }
136
137    /***
138     * This is a method only available within the package for
139     * implementing efficient datagram transport by elminating buffering.
140     * It takes a datagram as an argument, and a byte buffer in which
141     * to store the raw datagram data.  Inside the method, the data
142     * is set as the datagram's data and the datagram returned.
143     *
144     * @param datagram  The datagram to create.
145     * @param data The buffer to store the packet and to use in the datagram.
146     * @return The datagram argument.
147     ***/
148    @Override
149    DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
150    {
151        int length;
152
153        length = _message.length();
154
155        data[0] = 0;
156        data[1] = (byte)_type;
157        data[2] = (byte)((_error & 0xffff) >> 8);
158        data[3] = (byte)(_error & 0xff);
159
160        System.arraycopy(_message.getBytes(), 0, data, 4, length);
161
162        data[length + 4] = 0;
163
164        datagram.setAddress(_address);
165        datagram.setPort(_port);
166        datagram.setData(data);
167        datagram.setLength(length + 4);
168
169        return datagram;
170    }
171
172
173    /***
174     * Creates a UDP datagram containing all the TFTP
175     * error packet data in the proper format.
176     * This is a method exposed to the programmer in case he
177     * wants to implement his own TFTP client instead of using
178     * the {@link org.apache.commons.net.tftp.TFTPClient}
179     * class.
180     * Under normal circumstances, you should not have a need to call this
181     * method.
182     *
183     * @return A UDP datagram containing the TFTP error packet.
184     ***/
185    @Override
186    public DatagramPacket newDatagram()
187    {
188        byte[] data;
189        int length;
190
191        length = _message.length();
192
193        data = new byte[length + 5];
194        data[0] = 0;
195        data[1] = (byte)_type;
196        data[2] = (byte)((_error & 0xffff) >> 8);
197        data[3] = (byte)(_error & 0xff);
198
199        System.arraycopy(_message.getBytes(), 0, data, 4, length);
200
201        data[length + 4] = 0;
202
203        return new DatagramPacket(data, data.length, _address, _port);
204    }
205
206
207    /***
208     * Returns the error code of the packet.
209     *
210     * @return The error code of the packet.
211     ***/
212    public int getError()
213    {
214        return _error;
215    }
216
217
218    /***
219     * Returns the error message of the packet.
220     *
221     * @return The error message of the packet.
222     ***/
223    public String getMessage()
224    {
225        return _message;
226    }
227}